Damn, I had a long thread here, already to go, and I lost it. Oh well, I'll try again, but much shorter. I'm a complete beginner, and any system I had in place that worked would have been more good luck than good management, as I almost threw my system together at the start.
Two 100W panels in parallel, that were keeping up, for 5 years, are now not, having switched to 24V battery, instead of 12V. Originally 2 x 12V 110Ah SLA batteries in parallel, but now for various reasons, I wanted 24V, so I switched things around, and changed a lot of other things too, and am struggling. I was using a 20A PWM controller, and now have a 20A mppt controller, and 2 new batteries, again 12V, 110Ah, but now AGM, and in series.
Because I went to 24V, I had to put my panels in series too, otherwise I didn't have enough voltage, and now my system is struggling to keep up.
I only have a 4-6W continuous load so I don't have much to make up, but still, right now, even on a full sun day, I only get 25W. Yes, it's a net gain, but it's not enough, because here in the UK we can have many poor days in a row. On physically observing the installation, I see that there is very dappled sunlight on the panels. This is due to it being summer, and the sun tracking across the sky very high, and passing over, rather than in front of the trees that are behind and overhanging my cabin, and I'm wondering if changing to series panels has made my system far less tolerant of shading?
Also, at a full sun moment, my mppt controller is outputting less than the required bulk charge voltage, and I'm wondering if that too is compounding the issue? Maybe it's tracking the maximum power point, in this dappled sun, and that's at a voltage less than that of bulk? Either way, I'm just barely keeping up, though things may improve, ironically, as I move into autumn, as the sun tracks lower. Panels are angled to be optimised for winter, when things would theoretically be at their worst, to try and make up for that, so I wouldn't get perfect results, even if the sun could shine on them directly right now.
6W is all I need, and I could perhaps use a smaller battery, but I also use it with an inverter, for mains power when I'm there, infrequently, so I went with bigish batteries to cope with my inverter needs, and also to make sure I had cover for many days in a row, of rain.
Could it have made such a big change, switching to series panels, and an mppt controller, as a result of my dappled sun, or is it simply that I didn't check last year, when the results might have been the same? Basically, I hadn't noticed that the trees were shading my panels, when it tracks at or close to its highest, so I probably didn't check SOC, etc, thinking, it must be doing well, it's sunny. Embarrassingly, it's only this week, that I've noticed this issue, perplexed as to why I only had 25W in full sun. I can come further forward, on the roof, which brings them more into full sunshine, but perhaps, if I'm going up there to do that, I might be just as well to just replace them with a 500W panel instead.
On a rainy, full cloud day, I see I make just under 3W. Maybe with a 500W panel, fitted lower down the roof, I will make enough to at least keep up with my 6W demand during the day?
Which brings me to another question, there seems to be many types of panel, half cell, etc, etc, and also wildly varying prices. One thought I had was to buy two more identical 100W panels, series those together, and parallel them with the existing series panels, but two of those costs a lot more than I can get a 500W panel for, so what's going on there?
Current equipment:
Epever Tracer2210AN SCC
2 x 12V 110Ah AGM Batteries in series
2 x 100W Panels in series
Sadly, I cannot trim the trees, by the way, but here is a shot of the installation, in which you can see the dappled effect on the panels, whilst it's evident from the rest of the picture that it's pretty sunny.
Thanks for any thoughts.
Cheers
Sutty
Two 100W panels in parallel, that were keeping up, for 5 years, are now not, having switched to 24V battery, instead of 12V. Originally 2 x 12V 110Ah SLA batteries in parallel, but now for various reasons, I wanted 24V, so I switched things around, and changed a lot of other things too, and am struggling. I was using a 20A PWM controller, and now have a 20A mppt controller, and 2 new batteries, again 12V, 110Ah, but now AGM, and in series.
Because I went to 24V, I had to put my panels in series too, otherwise I didn't have enough voltage, and now my system is struggling to keep up.
I only have a 4-6W continuous load so I don't have much to make up, but still, right now, even on a full sun day, I only get 25W. Yes, it's a net gain, but it's not enough, because here in the UK we can have many poor days in a row. On physically observing the installation, I see that there is very dappled sunlight on the panels. This is due to it being summer, and the sun tracking across the sky very high, and passing over, rather than in front of the trees that are behind and overhanging my cabin, and I'm wondering if changing to series panels has made my system far less tolerant of shading?
Also, at a full sun moment, my mppt controller is outputting less than the required bulk charge voltage, and I'm wondering if that too is compounding the issue? Maybe it's tracking the maximum power point, in this dappled sun, and that's at a voltage less than that of bulk? Either way, I'm just barely keeping up, though things may improve, ironically, as I move into autumn, as the sun tracks lower. Panels are angled to be optimised for winter, when things would theoretically be at their worst, to try and make up for that, so I wouldn't get perfect results, even if the sun could shine on them directly right now.
6W is all I need, and I could perhaps use a smaller battery, but I also use it with an inverter, for mains power when I'm there, infrequently, so I went with bigish batteries to cope with my inverter needs, and also to make sure I had cover for many days in a row, of rain.
Could it have made such a big change, switching to series panels, and an mppt controller, as a result of my dappled sun, or is it simply that I didn't check last year, when the results might have been the same? Basically, I hadn't noticed that the trees were shading my panels, when it tracks at or close to its highest, so I probably didn't check SOC, etc, thinking, it must be doing well, it's sunny. Embarrassingly, it's only this week, that I've noticed this issue, perplexed as to why I only had 25W in full sun. I can come further forward, on the roof, which brings them more into full sunshine, but perhaps, if I'm going up there to do that, I might be just as well to just replace them with a 500W panel instead.
On a rainy, full cloud day, I see I make just under 3W. Maybe with a 500W panel, fitted lower down the roof, I will make enough to at least keep up with my 6W demand during the day?
Which brings me to another question, there seems to be many types of panel, half cell, etc, etc, and also wildly varying prices. One thought I had was to buy two more identical 100W panels, series those together, and parallel them with the existing series panels, but two of those costs a lot more than I can get a 500W panel for, so what's going on there?
Current equipment:
Epever Tracer2210AN SCC
2 x 12V 110Ah AGM Batteries in series
2 x 100W Panels in series
- Peak power: 100W
- Maximum power voltage: 19.3V
- Maximum power current: 5.18A
- Open circuit voltage: 22.9V
- Short circuit current: 5.56A
JA Solar 500W Mono MBB PERC Half-Cell Silver Rigid Solar Panel - JAM66S-30-500-MR-MC4
JA Solar 500W Mono Rigid Solar Panel - JAM66S-30-500-MR-MC4 Harness the sun's limitless energy with the 500W JA Solar Panel - JAM66S-30-500-MR-MC4,…
infinite-solar.co.uk
Sadly, I cannot trim the trees, by the way, but here is a shot of the installation, in which you can see the dappled effect on the panels, whilst it's evident from the rest of the picture that it's pretty sunny.
Thanks for any thoughts.
Cheers
Sutty
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